1. Field
Exemplary embodiments of the present invention relate to a manufacturing method for an organic light emitting diode (OLED) display. More particularly, exemplary embodiments relate to an OLED display having a curling-improved structure.
2. Discussion of the Background
Organic light emitting diode displays include organic light emitting elements that include a hole injection electrode, an organic emission layer, and an electron injection electrode. Each organic light emitting element emits light by energy generated when an exciton, generated by combining an electron and a hole in the organic emission layer, falls from an exited state to a ground state. Thus, the organic light emitting diode display displays a predetermined image by using this light emission.
In contrast to liquid crystal displays, organic light emitting diode displays have a self-luminance characteristic so a separate light source is not required. Thus, thickness and weight of the display may be reduced. Further, since organic light emitting diode displays exhibit desirable characteristics such as low power consumption, high luminance, and rapid response speed, organic light emitting diode displays are receiving attention as a next generation display device.
The organic light emitting diode (OLED) display has a panel structure in which a driving circuit unit and the organic light emitting element formed on a flexible substrate are protected by a thin film encapsulation (TFE) layer. In a process of forming the TFE layer, chemical vapor deposition (CVD) is used. However, when CVD is used, a flexible panel is greatly stressed by a strong compression characteristic of SiNx, so the panel may be bent. In addition, due to the bending characteristic (flexibility) of the flexible panel, when the force (tension or compression force) of the internal layers is not balanced, curling in one direction is generated.
In conventional display devices, upper and lower protection films are attached to flexible display panels. Since the upper protection film is designed to be removed later, an adhesive for the upper protection film is typically formed of silicon having low adhesion. In contrast, the lower protection film needs to be permanently attached, and thus, an adhesive for the lower protection film is typically formed of an acryl having high adhesion. However, the lower modulus of silicon compared to acryl when both the upper and lower protection films are attached to the flexible display panel generates curling toward the upper side of the upper protection film.
Such curling makes it difficult to perform various subsequent processes, such as vacuum adsorption, align key recognition, transport, and loading.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.